(a) Technical Field
The present invention relates to a fuel efficiency measurement system and method for a fuel cell vehicle, which can accurately measure fuel efficiency of a fuel cell vehicle.
(b) Background Art
Generally a fuel cell is considered as a future electricity generation system due to its high efficiency of electricity generation and its zero emission characteristic. The fuel cell has been extensively studied as a promising power source for a vehicle, which can solve various problems such as environmental pollution and global warming that has been recently issued.
The fuel cell is a device that converts chemical energy, generated by oxidizing a material having activity such as hydrogen (e.g. LNG, LPG, methanol, etc.) through an electrochemical reaction, directly into electrical energy. In general, the fuel cell uses hydrogen, which is easily generated from natural gas, and oxygen in air.
In case of a hydrogen fuel cell vehicle equipped with the above-described fuel cell that uses hydrogen as a fuel, it is impossible to measure fuel efficiency by a method applied to internal combustion engine vehicles, i.e., with the carbon content contained in the exhaust gas, and thus a new fuel efficiency measurement method for the hydrogen fuel cell vehicle is required.
The fuel efficiency measurement method applied to the hydrogen fuel cell vehicle shown in FIG. 1 includes measurement based on a change in temperature and pressure of a hydrogen tank 11, measurement based on an amount of hydrogen supplied to a fuel cell 14, and measurement based on the current of the fuel cell 14. In this case, sensors provided for the fuel efficiency measurement include a temperature sensor 1 and a pressure sensor 2 of the hydrogen tank 11, a flow sensor 3 for measuring the amount of hydrogen supplied to the fuel cell 14, and a current sensor 4 for measuring the current amount of the fuel cell 14.
The fuel efficiency of the hydrogen fuel cell vehicle is measured based on an amount of hydrogen used in the fuel cell 14 and a driving distance and expressed as gasoline equivalent fuel efficiency through an equivalent energy amount of hydrogen for the purpose of comparison with that of the internal combustion engine vehicle.
Like this, in calculating the fuel efficiency of the hydrogen fuel cell vehicle, it is important to accurately measure the amount of hydrogen supplied from the hydrogen tank 11, and the conventional fuel efficiency measurement methods have the following drawbacks.
Although the measurement method based on the change in temperature and pressure of the hydrogen tank has an advantage of calculating a hydrogen purge amount, the errors of the pressure and temperature sensors are large, and soaking is required.
Moreover, although the measurement method based on the amount of hydrogen supplied has an advantage of calculating the hydrogen purge amount, the error of the hydrogen flow sensor is quite large.
Furthermore, although the measurement method based on the current amount of the fuel cell has an advantage in that the calculation of the current amount and the reactivity are excellent, it is impossible to estimate the hydrogen purge amount and the error of the current sensor is quite large.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.